1. Field of the Invention
The present invention relates to an electronic component mounting apparatus for mounting an electronic component on a substrate and, more particularly, to a rotary driver that forms a part of the electronic component mounting apparatus and a method for processing of wiring.
2. Description of the Related Art
A structure of a conventional electronic component mounting apparatus 100 will now be described with reference to FIG. 4.
A rotary body 1 sequentially mounts various electronic components in predetermined positions on a substrate in variable mounting directions. The rotary body 1 is connected to a driver 3 through a first joint 2 for driving and is structured such that the driver 3 rotates the rotary body 1 by a predetermined amount in a reciprocating manner. The driver 3 is fixed to a fixed structure (frame or the like), which is not shown.
A component mounting section 18 is provided on the bottom of the rotary body 1, and the component mounting section 18 is connected to a driver 19 through a coupling shaft 17, which is possible to slide in the vertical and rotating directions. The component mounting section 18 is structured such that the component mounting section 18 moves up and down by a predetermined amount independently of the rotary body 1 when an electronic component is mounted in a predetermined position on a substrate.
The first joint 2 for driving includes a driving disc 4 provided on a rotary shaft of the driver 3, a driven disc 5 provided on the coupling shaft 17, and a driving belt 6 wound around and stretched between the driving disc 4 and the driven disc 5.
A wire 8 is a wire for an electric component such as a sensor incorporated in the rotary body 1. The wire 8 is guided such that it extends along the exterior of a guide plate 9 formed like a disc and is fixed to an upper end of the rotary body 1 with a fixing component 10 at one end of the wire 8. The position in which the wire 8 is fixed is referred to as “fixing point A”. The wire 8 is attached to a movable block 13 in an intermediate position of the same, and the mounting position is referred to as “intermediate support point B”.
The movable block 13 is attached to a slide block 16. The slide block 16 is supported and guided by a rectilinearly movable guide section 14 and is structured to move on a linear path 15 toward and away from the rotary body 1. In other words, the slide block 16 is structured to make a reciprocating motion. An upper end of the movable block 13 is connected to the driver 3 through a second joint 20 for driving disposed along the rectilinearly movable guide section 14.
The second joint 20 for driving includes a driving disc 21 provided on a rotary shaft of the driver 3, a driven disc 22 provided on a rotary shaft of the main body of the apparatus, and a driving belt 23 wound around and stretched between the driving disc 21 and the driven disc 22.
The movable block 13 is connected with the driving belt 23. Therefore the rotary body 1 is rotated through the first joint 2 for driving, and the movable block 13 is moved on the linear path 15 in synchronism with the rotation of the rotary body 1 through the driving belt 23 that forms a part of the second joint 20 for driving, when the driver 3 is operated.
The other end of the wire 8 is fixed to a fixing block 27 on the main body of the apparatus, and the fixing position is referred to as “fixing point C”.
The wire 8 is formed into a straight line between the fixing point A to the intermediate support point B, which is referred to as “straight section 30”. Further, the wire 8 is formed into a spiral, which can expand and contract, between the intermediate support point B and the other fixing point C, which is referred to as “coil section 31”. Therefore, when the movable block 13 moves on the linear path 15, the amount of a change in the distance from the intermediate support point B to the other fixing point C as a result of the movement of the intermediate support point B can be absorbed by the coil section 31. Moreover, the wire 8 has another straight section located beyond the fixing point C.
Nevertheless, the conventional electronic component mounting apparatus has the following problems. The speed of the driver 3 may be increased to reduce the cycle time of the electronic component mounting apparatus or, in other words, to increase the speed of rotation in order to reduce the time required for the rotary body 1 to make a rotary motion to change the mounting direction. In this case, however, the life of the belt is significantly reduced because there is an increase in the tensile force acting on the driving belt 6 wound and stretched as described above.
Further, the driving belt 6 is wound around stretched between the driving disc 4 and driven disc 5, a slip or tooth miss-engagement can occur because of increasing in forces acting on contact areas between the driving disc 4 and driving belt 6, and between the driven disc 5 and driving belt 6.
Furthermore, residual vibrations increase when the rotary body 1 stops because of an increase in the acceleration or deceleration speed of the rotation. The residual vibrations have resulted in various problems including a reduction in the positional accuracy of component mounting.
Referring to the wire 8 of the electric product included in the rotary body 1, it has a structure in which the amount of a change in the distance from the intermediate support point B to the fixing point C, which is attributable to the movement of the intermediate support point B during the rotation of the rotary body 1, is absorbed by the coil section 31 (the curled section). However, when the rotating speed of the rotary body 1 is increased, a load applied to the wire 8 increases in the vicinity of the wire fixing portions at the intermediate support point B and the fixing point C. The reason the load increases is that a speed of expansion and contraction of the coil section 31 also increases, which is caused by a high-speed moving of the intermediate support point B according to the increasing of the rotating speed.
Since the vibration and the speed of expansion and contraction of the coil section 31 increase, circles of the coil contact each other with a greater force when the coil section 31 expands and contracts, which has resulted in a problem in that the life of the wire 8 is reduced.
Further, the joint 2 for driving must be provided in addition to the driver 3 in order to rotate the rotary body 1, and a wire-processing unit must be provided in order to process the wire 8. This has resulted in increases in the size of the facility and the number of components, and such increases have led to a cost increase.